// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.


void f(Object x) {
  while (x is String) {
    x.length;
  }
  x.length; //# 01: compile-time error
}

void main() {}
